Philadelphia English and New York City English had a common ancestor dialect that likely existed in the 1800s, since both modern dialects demonstrate a high/ɔː/ vowel (creating a contrast between words like cot and caught) as well as a phonemic split of the short a vowel, /æ/ (making gas and gap, for example, have different vowels sounds).[5] One important indicator of this is that Philadelphia's short a split is documented as being a simplified variant of New York City's split.[6] Unlike New York City English, however, most speakers of Philadelphia English have always used a rhotic accent (meaning that the r sound is never "dropped").

In the late 1800s until the 1950s, the Philadelphia accent shifted to sound more like one of the emerging (and now-common) regional accents of the American South/Midland, for example in fronting /oʊ/, raising /aʊ/, and even some reported weakening of /aɪ/.[7] The Philadelphia accent even began retreating away from its longstanding New York City-like features, developing more of its own entirely unique features, discussed further below.[8] Higher-educated Philadelphians born in or since the last quarter of the 1900s are also showing remarkable regularity in replacing the traditional Philadelphia /æ/ split with a General American-like tensing of /æ/ only before nasal consonants; this probably began around the time the first of these generations attended college.[9] Of the younger Philadelphia accent, "the most strongly supported generalization is that Philadelphia has moved away from its Southern heritage in favor of a Northern system, avoiding those forms that are most saliently associated with local phonology".[8]

The vowels in Philadelphia speech show volatility, as Labov's research has identified changes affecting over half of the vowel phonemes.

A feature shared by Philadelphians, New Yorkers, and southern New Englanders is the raising and diphthongizing of /ɔː/ to [oə] or even higher [o̝ə]. The raised variants often appear as diphthongs with a centering glide. As a result, Philadelphia is resistant to the cot–caught merger. Labov's research suggests that this pattern of raising is essentially complete in Philadelphia and seems no longer to be an active change.

One of the features that Philadelphia shares with Midland dialects (and one absent from New York speech) is the fronting of /oʊ/ and /uː/; the resulting allophones are around [ɜʊ] and [ʉu], respectively. Generally, greater degrees of fronting are heard when the vowels appear in "free" positions (i.e., without a following consonant) than in "checked" positions (i.e., with a following consonant). Fronting does not occur in the context of following liquids leading to a significant difference between, e.g., goat and goal. The fronting of /oʊ/ and /uː/ is well established in Philadelphia, though cross-generational data show that it remains an active change. Fronted nuclei in /aʊ/ are well established in Philadelphia speech as in New York. More recent research has noted a tendency among the middle-aged and younger generation of Philadelphians to raise the vowel, resulting in [ɛɔ].

/ʊ/, the vowel in foot, is sometimes fronted though not to the degree seen with /oʊ/ and /uː/.

As in New York City English and Baltimore English, historical "short a" has split into two phonemes: lax /æ/ (as in bat) and tense /eə/ (as in bath). Their distribution in Philadelphia along with Baltimore, however, is different from that of New York City: for instance, the words mad (tense) and sad (lax) do not rhyme in Philadelphia or Baltimore, but do for New York City and most other English dialects. Not all Philadelphians have this feature and some are beginning to favor the more General Americantensing of short a only before nasals (especially under the influence of youth trends and higher education); in fact, as a general rule, native Philadelphians only consistently have this split system if their own parents are native Philadelphians.[10] For more details on the Philadelphia, Baltimore, and New York systems see: phonemic /æ/ tensing in the Mid-Atlantic region or click "show" below.

The Philadelphia/Baltimore short-a split compared to the
New York City short-a split and General American /æ/ tensing

The NYC, Philadelphia, and Baltimore dialects' rule of tensing /æ/ in certain closed-syllable environments also applies to words inflectionally derived from those closed-syllable /æ/ environments that now have an open-syllable /æ/. For example, in addition to pass being tense (according to the general rule), so are its open-syllable derivatives passing and passer-by, but not passive.

As in New York, Boston, and most native dialects of English outside North America, there is a three-way distinction between Mary[ˈmeɹi]~[ˈmeəɹi], marry[ˈmæɹi], and merry[ˈmɛɹi]~[ˈmɜɹi]. However, in Philadelphia some older speakers have a merger (or close approximation) of /ɛ/ and /ʌ/ before /ɹ/ (the furry–ferry merger), so that merry is merged instead with Murray (with both pronounced as something like [mʌɹi]). Labov, Ash, and Boberg (2006: 54) report that about one third of Philadelphia speakers have this merger, one third have a near-merger, and one third keep the two distinct. Relatedly, as in New York, many words like orange, Florida, and horrible have /ɑ/ before /ɹ/ rather than the /ɔɹ/ used in many other American dialects (See: Historic "short o" before intervocalic r).

Canadian raising, as in General American, occurs for /aɪ/ (as in price) but not for /aʊ/ (as in mouth) (Labov, Ash, and Boberg 2006: 114–15, 237–38). Consequently, the diphthong in like may begin with a nucleus of mid or even higher position [lʌik], which distinguishes it from the diphthong in live[laɪv]. Canadian raising in Philadelphia occurs before voiceless consonants, and it is extended to occur before some voiced consonants as well, including intervocalic voiced stops as in tiger and spider. Fruehwald argues[11] that /aɪ/ has actually undergone a phonemic split in Philadelphia as a result of Canadian raising. The raising of /aɪ/ is unusual as the innovators of this change are primarily male speakers while the other changes in progress are led primarily by females. The sociolinguistic evidence suggests this raising is a fairly recent addition to Philadelphia speech.

Early descriptions of Philadelphia speech indicate lowered and/or laxed variants of /iː/ were common. The recent sociolinguistic evidence indicates a reversal of this trend such that the vowel is now commonly raised and fronted. This raising is heard primarily before consonants (e.g., eat).

The Linguistic Atlas researchers recorded lax variants of /eɪ/ near [ɛɪ]. As with /iː/, recent research suggests this trend is being reversed by raising and fronting of the vowel often to a position well beyond [e]. This raising occurs before consonants (e.g., paid); in word-final position (pay), /eɪ/ remains lowered and lax.

Many Philadelphians use a rather high and back vowel for /ɑr/ as in start; something near [ɔ]. The so-called horse–hoarse merger takes place, and the merged vowel is typically mid to high back; it can be as high as [ʊɚ]. As noted in New York, these tendencies toward backing and raising of /ɑr/ and /ɔr/ may constitute a chain shift. The evidence suggests the movement of /ɑr/ began this shift, and this vowel is relatively stable today, while generational differences are heard in the shifting of /ɔr/.

/ɔɪ/, as in choice, may be more raised than in other dialects; sometimes it is as high as [ʊɪ].[12]

/ʌ/, as in strut, may show raised and back variants. In some cases, the vowel is in the high, back corner of the vowel space near /u/. This is reportedly a recent development and is one more common among male speakers.

Labov's research has indicated a tendency toward lowering of the lax vowels /ɪ/ and /ɛ/. This pattern is not yet well established and is labeled by Labov as an "incipient" change.

Philadelphia forms the core of the only traditionally rhotic area of the American East Coast.[13] This area runs from Pennsylvania and South Jersey down to Delaware and northern Maryland, and remains fully r-pronouncing today.

Non-rhoticity (r-dropping) can be found in some areas of Philadelphia, such as among working-class male speakers specifically from South Philadelphia, especially those born in the first half of the 1900s and of Italian or Jewish descent.[14][15] On the other side of the socioeconomic spectrum, non-rhoticity in speakers from the Philadelphia Main Line may be a result of wealthy families sending their children to expensive boarding schools in the United Kingdom up until the 1960s.[16] Non-rhoticity is most prevalent among black Philadelphians, who largely do not demonstrate the regional speech features of Philadelphia English;[10] instead, many black Philadelphians speak African American Vernacular English.

Consonant changes, especially reductions and lenitions, are very common in informal conversational speech, so that:

The sibilant /s/ is palatalized to [ʃ] (as in she) before /tr/. Thus, the word streets might be pronounced "shtreets" [ˈʃtɹits].[17]

L-vocalization is quite pervasive in Philadelphia speech. Phonetically it may be realized as something like [o] or a velar or labio-velarglide, [ɰ] or [w], or the consonant may be deleted altogether. Among Philadelphians, as in other dialects, vocalization occurs quite frequently in word-final and pre-consonantal contexts (e.g., mill, milk). In a more unusual development, vocalization may also occur inter-vocalically in Philadelphia. This tendency is more common when /l/ appears following low vowels bearing primary word stress (e.g., hollow). This variable also shows some lexical conditioning, appearing, for example, with exceptionally high frequency in the pronunciation of the name of the city (Ash 1997). This, in part, leads to the stereotype of Philadelphia being pronounced as "Fluffya" or "Filelfia."[1]

As in other areas, the interdental fricatives /θ/ and /ð/ are often realized as stops, [t] and [d] or affricates [tθ] and [dð] in Philadelphia speech. This variation appears to be a stable class-stratified feature with the non-fricative forms appearing more commonly in working class speech.

The yew–hew merger can be found, as in New York City, in which words like human and huge, which begin with an /hj/ cluster, the /h/ is commonly deleted giving [ˈjumən] and [judʒ].

Consonant clusterreductions, such as removing the "t" sound from consonant clusters, so that "mustard" sounds more like "mussard," or "soft" like "sawff."[1]

On may be pronounced [ɔən], so that, as in the South and Midland varieties of American English (and unlike New York) it rhymes with dawn rather than don. However, Philadelphia has been noted as featuring, at least among some speakers, the Northern /ɑ/ in on (Kurath and McDavid 1961).

The word water is commonly pronounced [ˈwʊɾəɹ] (with the first syllable rhyming with the word put, so that it sounds like wooter.) This is considered by many to be the defining characteristic of the Philadelphia dialect.[18]

The word towel is commonly pronounced the same as tal in the word tally.[13]

Both long-e and long-a sounds are shortened before /ɡ/. Eagle rhymes with giggle[ˈɪɡəɫ] (as in "the Iggles"); league[ɫɪɡ] rhymes with big ; vague and plague rhyme with peg (pronounced [vɛɡ] and [pʰɫɛɡ], respectively).[19] For some Philadelphians, colleague and fatigue also have /ɪ/ (pronounced [ˈkʰɑɫɪɡ] and [fəˈtʰɪɡ], respectively). However, these are words learned later, so many use the more standard American [ˈkʰɑɫiɡ] and [fəˈtʰiɡ].[13]

In words like gratitude, beautiful, attitude, Baltimore, and prostitute, the i may be pronounced with a long ee sound [i], as in bee.[13]

Many words ending in -ow or -o, such as window, widow, tomato, or casino, are pronounced with a schwa ending (like the indistinct vowel sound at the end of the word coda). Thus, windows would be pronounced [ˈwɪndəz] and tomorrow would be pronounced [tʰəˈmɑɹə].[citation needed]

Many Philadelphians are known to use the expression "youse" both as second person plural and (rarely) second person singular pronoun, much like the mostly Southern / Western expression "y'all" or the Pittsburgh term, "yinz". "Youse" (often "youse guys" when addressing multiple people) is common in many working class northeastern U.S. areas, but is often associated with Philadelphia especially. The pronunciation reflects vowel reduction more often than not, yielding /jəz/ and /jɪz/ ("yiz") just as often as the stereotypical /juːz/. (ex: "Yiz want anything at the store?" "Yiz guys alright over there?").[23][24][25][26] Second person singular forms commonly are heard as /jə/ and /jɪ/.

A sandwich consisting of a long bread filled with lunch meat, cheese, and lettuce, onion and tomato, variously called a "sub" or "submarine sandwich" in other parts of the United States, is called a hoagie. Olive oil, rather than mayonnaise, is used as a topping, and "hot" or "sweet" peppers are used for spice. The term 'hoagie' originated in Philadelphia.[28][29][30] A similar sandwich toasted in an oven or broiler is called a grinder.[31][32]

Small chocolate or multi-colored confections sprinkled on ice cream and cake icing, elsewhere called sprinkles are known as jimmies in the Philadelphia area, as well as in the Boston (although only chocolate ones are Jimmies in Boston) and Pittsburgh areas.

Movies and television shows set in the Philadelphia region generally make the mistake of giving the characters a working class New York dialect (specifically heard in films set in Philadelphia such as the Rocky series, Invincible, and A History of Violence). A contrary example is the character of Lynn Sear (played by Toni Collette) in The Sixth Sense, who speaks with an accurate Philadelphia dialect. In the film Sleepers, Kevin Bacon, a Philadelphia native, uses an exaggerated Philadelphia accent for the character of Sean Nokes.

The use of geographically inaccurate dialects is also true in movies and television programs set in Atlantic City or any other region of South Jersey; the characters often use a supposed "Joisey" dialect, when in reality that New York-influenced dialect for New Jersey natives is almost always exclusive to the extreme northeastern region of the state nearest New York City.[1] An important factor here is that in the real world, "local" TV, political, and sports personalities in South Jersey and part of Central Jersey are culturally associated with Philadelphia, not New York City.

^Labov et al., 2006, p. 173: "In NYC and the Mid-Atlantic region, short-a is split into a tense and lax class. There is reason to believe that the tense class /æh/ descends from the British /ah/ or 'broad-a' class."

^Labov, William (2008). "Mysteries of the substrate". In Miriam Meyerhoff and Naomi Nagy (eds.). Social Lives in Language Sociolinguistics and multilingual speech communities. Amsterdam/Philadelphia: John Benjamins. pp. 320.